Apparatus for casting metal strip

ABSTRACT

APPARATUS FOR CONTINUOUSLY CASTING METAL STRIP ON A CONTINUOUSLY COOLED MOVING BELT INCLUDES MEANS AROUND WHICH THE BELT IS TRAINED TO FORM A SMALL DEPENDENT LOOP WITHIN A LARGER LOOP, AND END PIECES THAT COOPERATE WITH THE SMALL LOOP TO MAKE A RESERVOIR INTO WHICH MOLTEN METAL IS TEEMED AND IN WHICH IT SOLIDIFIES AGAINST THE INSIDE SURFACE OF THE BELT.

pt- 20, 1971 c. c. GERDING 3,605,867

APPARATUS FOR CASTING METAL STRIP Filed June 30, 1970 3 Sheets-Sheet 1uwsmon CHARLES C. GERDING his ATTORNEY Sept. 20, 1971 c. c. GERDINGAPPARATUS FOR CASTING METAL STRIP 3 Sheets-Sheet 2 Filed June 30, 1970INVENTOR CHARLES CHRISTIAN GERDING his ATTORNEY p 20, 1971 c. c. GERDING3,605,867

APPARATUS FOR CASTING METAL STRIP Filed June 30, 1970 3 Sheets-Sheet SINVENTOR CHARLES C. GERDING his ATTORNEY Patented Sept. 20, 19713,605,867 APPARATUS FOR CASTING METAL STRIP Charles Christian Gerding,Pittsburgh, Pa., assignor to Jones & Laughlin Steel Corporation,Pittsburgh, Pa. Filed June 30, 1970, Ser. No. 51,276 Int. Cl. B22d 11/06US. Cl. 164278 18 Claims ABSTRACT OF THE DISCLOSURE Apparatus forcontinuously casting metal strip on a continuously cooled moving beltincludes means around which the belt is trained to form a smalldependent loop within a larger loop, and end pieces that cooperate withthe small loop to make a reservoir into which molten metal is teemed andin which it solidifies against the inside surface of the belt.

Molten metal has heretofore been continuously cast into strip bybringing it into contact with a chill roll or pair of rolls, a ring, asubstantially flat endless belt, or between a ring and a belt. Apparatuswhich solidifies the metal against the convex surface of a roll or ringthe external surface of which is immersed in the molten metal has thedisadvantage that the metal solidifies from the surface of the pool, onwhich float undesired metalloids, fragments of refractory slag, oxides,gas bubbles and other impurities. Apparatus which casts the molten metalon a flat belt wherein the belt contains a pool of metal must have edgebarriers of some sort which are difficult to maintain in operatingcondition. Apparatus has been proposed to cast molten metal on theinside surface of a ring with integral end pieces, but the problem thenbecomes that of getting the cast strip out of the ring. Suggestions havebeen made to spiral the cast strip out through an open end of the ringbut unless a very large diameter ring is employed this createsdifiiculties except for narrow strip of ductile material.

There is, however, a very real advantage in casting strip against theinside of a ring or like concave surface which contains the molten metalpool. The bottom cast material is free from the floating contaminantsabove mentioned.

It is an object of my invention therefore to provide apparatus forcontinuously casting strip from the bottom of a pool of molten metal,and withdrawing it therefrom. It is another object to provide suchapparatus which casts the metal against the concave surface of a movingbelt. It is another object to provide such apparatus which permitsremoval therefrom of wide metal strip of a variety of properties withoutdifliculty. Other objects of my invention will appear in the descriptionthereof which follows:

I have found that the objects above mentioned are achieved withapparatus in which an endless metal belt is trained into an open toploop on the inner surface of which the strip is cast. Embodiments of myinvention presently preferred by me are illustrated in the attachedfigures to which reference is now made.

FIG. 1 is an isometric view of apparatus of my invention, some detailsof which are omitted for the sake of clarity.

FIG. 2 is an isometric view of a modified form of the apparatus of myinvention.

FIG. 3 is an isometric view of a portion of a further modified form ofthe apparatus of my invention.

FIG. 4 is a diagrammatic sketch of auxiliary strip bending apparatusused with my invention.

In my apparatus, an endless metal belt is trained around a plurality ofrolls having the axes parallel. Two of those rolls are positioneduppermost and are spaced from one another. The belt is looped over thoserolls and depends therebetween to form an inner loop. The inner loop ismaintained in a circular position by two circular end pieces. Moltenmetal is introduced into the reservoir formed by the inner loop and itsend pieces to form a pool in the bottom thereof. As the belt travelsaround the rolls molten metal from the pool solidifies against the innersurface of the inner loop as a relatively thin strip which emerges fromthe reservoir through its open top portion between the two rolls abovementioned. This cast strip is then sheared or rolled or otherwisedisposed of.

FIG. 1 illustrates a working form of the apparatus of my invention. Anendless metal belt 10 passes around upper rolls 11 and 12 and lower roll14. For a purpose to be described, an adjustable tracking roll 30 isspaced a distance from roll 11 and an adjustable tension roll 31 ispositioned so as to cause the belt 10 to travel around approximatelyhalf the circumference of roll 30. A second idler roll 32 is positionedbelow roll 31 so that the belt 10 from roll 31 passes around roll 32 andback to roll 14. Inner loop 15 of belt 10 passes around a pair ofcylindrical end pieces 33 and 34 so as to form a reservoir for moltenmetal. End piece 33 is carried by shaft 35 which is journaled in housing36 and end piece 34 is carried by shaft 37 which is journaled in housing38. Shaft 40 of roll 14 is driven by a motor 41 through gear reducer 42.

Above roll 14 in housings 4848 are positioned pinch rolls 49 and 50 withtheir axes parallel to roll 14. A launder or feedpipe 52 is positionedso as to discharge metal in the gap between rolls 11 and 12 into thereservoir formed by inner loop 15.

Roll 30 previously mentioned is mounted in a housing 53 which isadjustably supported on a base 54. The position of roll 30 is adjustedby conventional means so as to cause belt 10 to track properly aroundthe rolls and the circular end pieces of my apparatus. Roll 31 ismounted so as to be adjusted by conventional means not shown to maintainthe desired tension in belt 10.

Each end piece 33 and 34 comprises a metal shell 56 provided with arefractory lining 57. The outer face of each shell 56 extends radiallyas a flange 78, between which flanges belt 10 is confined laterally. Theoutside surface of inner loop 15 is supported by a plurality of rollssuch as roll 58, arranged circu-mferentially so as to sustain the weightof the molten metal in the loop. Cooling liquid spray nozzles 5959 arepositioned around the outer surface of inner loop 15 so as to cool thebelt 10 continuously as it travels around end pieces 33 and 34.

In the embodiment of my apparatus shown in FIG. 2, the rolls 61 and 62which define the open portion of inner loop 15 are not located in ahorizontal plane but in a tilted plane so that the opening they defineis not the uppermost portion of inner loop 15. Rolls 63 and 64 whichprovide for the outer loop are likewise displaced from the arrangementshown in FIG. 1. One circular end piece 65, otherwise similar to endpieces 33 and 34 above described, is provided with a central opening 66through which the launder or feedpipe 67 introduces molten metal intothe reservoir formed by the end pieces and inner loop 15. Each end piece65 is supported by one or more lower rolls 76 formed with acircumferential groove 77 into which flange 78 of end piece 65 fits.Rolls 61 and 62 are provided with like grooves 77, which also engageflange 78. Belt 10 travels around rolls 61, 62, 63, 64, and end pieces65, and the solidified strip 22 is removed as the belt 10 passes aroundroll 62 in clockwise direction. If it travels counter-clockwise, thestrip 22 is removed as belt 10 passes over roll 61. The external surfaceof loop 15 is cooled by cooling spray nozzles, not shown, similar tonozzles 59 in FIG. 1.

The inside upper portion of end piece 66 is heated by a gas burner 84.

In the embodiment of my invention illustrated in FIG. 3, the inner 100p15 of belt is made shallow. The molten metal reservoir is formed by loopand stationary segmental side boards or end pieces 68 and 73 disposedparallel to each other at the margins of belt 10 between rolls 11 and12. End pieces 68 and 73 are made of refractory material or of the samemetal as is being cast and are prevented from moving upward and fromturning by static restraints 79 and from moving outwardly by rotatingcontour rings 69 and 70, respectively, which are made of high thermalconductivity material. These rings are supported by rolls 11 and 12 andbear against the margins of belt 10 throughout inner loop 15. Contourring 70 is maintained in an upright position by flanged rolls 71 and 72which bear against the upper portion of its circumference and contourring 69 is provided with like rolls 74 and 75. The belt 10 is heldagainst the arcuate edges of end pieces 68 and 73 and in contact wtihcontour rings 69 and 70 by the rolls 11 and 12 and, if necessary, byauxiliary rolls such as roll 58 shown in FIG. 1. Contour rings 69 and 70are not driven rings but are rotated by the friction of belt 10. In thisembodiment of my invention, belt 10 is moved by driving rolls 11 and 12,or other rolls around which belt 10 is trained. Molten metal isconveniently introduced into inner loop 15 through the open end ofcontour ring 69 or 70 by a launder such as launder 67 in FIG. 2. Thesolidified strip 22 is taken off as belt 10 passes over roll 12. Theouter surface of loop 15 is cooled by cooling fluid spray nozzles 59-59.The return path of belt 10 is not shown, as it is similar to that ofFIG. 1.

The operation of my apparatus Will be described with particularreference to FIG. 1. Counter shaft 40 is retated so as to cause belt 10to travel around the belt rolls there illustrated. The portion of belt10 which passes around end pieces 33 and 34 forms a clockwise travellinginner loop 15, as has been described. The cooling liquid spray nozzlesare adjusted to spray cooling liquid on the outer surface of inner loop15. Molten metal is poured into the reservoir formed by inner loop 15and end pieces 33 and 34 through launder 52. As the belt 10 rotatesmolten metal freezes against the concave surface of that portion of belt10 which forms inner loop 15 and passes out of that reservoir where belt10 travels around roll 11. The solidified strip 22 so formed is lead topinch rolls 49 and 50 and is continuously removed thereby. I have foundthat if the margin of belt 10 overlaps the cylindrical sur faces of endpieces 33 and 34 there is no leakage of molten metal at the interface.The continuous cooling of the outer surface of inner loop 15 by coolingliquid spray nozzles 59 tends to freeze any metal which penetratesbetween those faces.

In some circumstances it may be convenient to take the solidified stripout of my apparatus in a path other than one tangential to the innerloop 15. FIG. 4 illustrates diagrammatically apparatus suitable for usein conjunction with the apparatus of FIG. 1 for bending the strip backover the roll adjacent its take off point. Positioned above roll 11 andtangent to the outside of the path of the strip 22 is fulcrum roll 81.Tangent to the inside of the path of the strip 22 and intermediate rolls11 and 81 is positioned guide roll 82, and above it is positioned roll83 which is adjusted to hold the solidified strip 22 against fulcrumroll 81. The strip 22 leaves the belt 10 as that belt passes over roll11. The strip then passes over roll 82 and between rolls 81 and 83. Asit leaves roll 81 it is bent into the desired take off path.

In apparatus for casting strip on a cooled belt such as I havedescribed, the surfaces in contact with the molten metal against whichthe molten metal does not solidify necessarily tend to extract heat fromit. Where those surfaces move with the belt, as do end pieces 33 and 34of FIG. 1, elements of the surface pass from positions below the metallevel to positions above the metal level as the end pieces rotate. Inthe latter positions, those elements give off heat. It is thereforedesirable from the standpoint of heat conservation to maintain a deeppool of molten metal in inner loop 15 Where those surfaces do not movewith the belt, as is the case with elements 68 and 73 in FIG. 3, it isdesirable from the heat loss standpoint not to extend them above themolten metal level any farther than is necessary, and apparatus of thistype is well suited for casting metal from a relatively shallow pool. Inapparatus of the type shown in FIG. 2, it is frequently desirable tosupply heat to the portion of rotating end piece 66 above the level ofthe molten metal, as by gas burner 84, to make up heat losses from theend piece. Under some circumstances, I find it desirable to heat theupper portions of end pieces 33 and 34 of FIG. 1 in the same way. Anyconventional method of heating those surfaces is satisfactory.

The endless belt 10 common to all the embodiments of my invention hereindescribed is caused to move by driving one or more of the rolls aroundwhich it is looped. In FIG. 1, roll 14 is driven. In the apparatus shownin FIG. 2, one or more of rolls 61, 62 and 76 which support end piece 65are driven or, if more convenient, the drive is furnished through one orboth of rolls '63 and 64. In the embodiment of FIG. 3, it is desirableto drive one or both of rolls 11 and 12. The solidified strip 22 is inall embodiments withdrawn from my apparatus by suitable positioneddriven pinch rolls, such as rolls 49 and 50 in FIG. 1. The strip afterleaving those rolls is further rolled to reduce its thickness or isotherwise treated as is desired.

I claim:

1. Apparatus for the production of cast metal strip by the continuoussolidification of molten metal on a chill surface comprising an endlessmetallic belt, means around which the belt is trained so as to form adependent loop, said means including a pair of discrete end pieces whichform with the loop an arcuate chamber adapted and adjusted to hold asegmental pool of molten metal, the chamber being open over a portion ofits upper periphery, means for supplying molten metal to the chamber,means for applying cooling fluid to the belt around the outside of theloop so as to cause molten metal to soiidify against the inside of theloop, means for Withdrawing solidified strip from the belt through theopen portion of the chamber, and means causing the belt to travel aroundthe training means.

2. Apparatus of claim 1 in which the means around which the belt istrained include a pair of parallel spaced apart rolls which with the endpieces define the open portion of the chamber periphery.

3. Apparatus of claim 1 in which the means for supplying molten metal tothe closed chamber are positioned to deliver the metal into the openportion of the chamber periphery.

4. Apparatus of claim 1 in which the end pieces comprise rotatable disksWhich contact the inside margins of the belt and travel with it, andincluding means for rotatably supporting those disks.

5. Apparatus of claim 4 in which the inside margins of the belt overlapcircumferential edge portions of the rotatable disks.

6. Apparatus of claim 4 in which the circumferential edges of therotatable disks are provided with radial outwardly extending flangesadjacent the outer faces of the disks and the inside margins of the beltoverlap the circumferential edges of the rotatable disks and abut theflanges.

7. Apparatus of claim 1 including supporting means positioned around theoutside of the loop.

8. Apparatus of claim 7 in which the supporting means comprise aplurality of freely rotatable rolls the axes of which are parallel.

9. Apparatus of claim 1 including means for maintaining tension in thebelt.

10. Apparatus of claim 1 including means for shifting the belttransversely of its direction of travel to maintain tracking.

11. Apparatus of claim 1 including means for applying heat to theexterior surface of an end piece.

12. Apparatus of claim 1 in which one end piece is provided with anopening and the means for supplying molten metal to the closed chamberextend into that opening.

13. Apparatus of claim 1 in which the end pieces comprise rotatabledisks provided with radial outwardly extending flanges adjacent theirouter faces and including supporting rolls therefor provided withgrooves which mate with those flanges.

14. Apparatus of claim 1 in which the end pieces comprise stationarysegments, and including means for maintaining the circumferential edgesthereof in sliding con- 15 17. Apparatus of claim 16 in which the meanscontacting the inside margins of the belt comprise rotatable rings.

18. Apparatus of claim 17 including grooved rolls positioned to maintainthe rotatable rings upright, the grooves of the rolls mating with therotatable rings.

References Cited UNITED STATES PATENTS 3,326,271 6/1967 Cofer 164--2783,464,483 9/1969 Cofer et a1. 164-278 3,509,937 5/1970 Radd 164-276XFOREIGN PATENTS 22,943 8/1910 Great Britain 164-276 ROBERT D. BALDWIN,Primary Examiner U.S. Cl. X.R. 164-87

